Time limits for holding logs to achieve successful antisapstain treatment
D R Eden, R N Wakeling, C M Chittenden, J G Van der Waals, B Carpenter
The purpose of these trials was to determine the maximum time that logs can be left in winter and summer before treatment if sapstain, caused by pre-treatment infection, was to be prevented. Pre-treatment storage conditions representative of average temperature and humidity for the winter months of June, July and August, and of moderately severe summer conditions, for the Bay of Plenty, New Zealand were employed. After felling and debarking, logs were artificially inoculated with Ophiostoma piceae and Diplodia pini and stored in a well ventilated room at 8°C and 88% RH. At predetermined intervals from the time of felling, including 8 hours (no time in storage room), 24 hours and then at 24 hourly intervals up to 7 days, a sample of log billets was treated with a commercial antisapstain formulation, and stored at ambient temperatures (from July to November or from February to April) in a well ventilated, open-sided barn. Billets were cross-cut into sections 8 and 16 weeks from the time of felling (winter), 8 weeks (summer), and assessed for the presence of internal sapstain. Results showed that for representative winter conditions (8°C and 88%RH) logs could be stored for periods of up to 4 days before treatment without adversely affecting posttreatment sapstain development. However, during reresentative summer conditions (storage at 25°C and 75%RH), storage for more than 8 hours prior to treatment resulted in unacceptable posttreatment sapstain development. Reasons for these differences are discussed.